*2.5. Origins Estimated by DNA Combing*

To estimate how many origins are activated (on average) during the S-phase in any organism, we develop a simple mathematical equation. This equation uses a ratio between the size of the chromosome in question (N), and the inter-origin distance (IOD) obtained by DNA combing to estimate, on average, the total number of origins fired during the S-phase. The equation is given by:

$$\text{Oc} = \left[\frac{N}{IOD}\right].\tag{4}$$

If the right-hand side of this equation results in a fraction of a unit, then the next higher integer unit must be taken as the result of the inequation, which is represented by the ceiling function (⌈ ⌉).

#### **3. Results and Discussion**
